Reproducibility of the Index of Orthognathic Functional Treatment need Scores Derived from Plaster Study Casts and their Three-dimensional Digital Equivalents: A pilot Study

Abstract

Objective

To determine the reproducibility of Index of Orthognathic Functional Treatment Need (IOFTN) scores derived from plaster casts and their three-dimensional (3D) digital equivalents.

Design

Pilot study, prospective analytical.

Setting

UK hospital orthodontic department.

Participants

Thirty casts and their digital equivalents, representing the pre-treatment malocclusions of patients requiring orthodontic-orthognathic surgical treatment, were scored by four clinicians using IOFTN.

Methods

Casts were scanned using a 3Shape digital scanner and 3D models produced using OrthoAnalyzer^TM (3Shape Ltd, Copenhagen, Denmark). Examiners independently determined the IOFTN scores for the casts and digital models, to test their inter- and intra-operator reliability using weighted Kappa scores.

Results

Intra-operator agreement with IOFTN major categories (1–5: treatment need) was very good for plaster casts (0.83–0.98) and good-very good for digital models (0.78–0.83). Inter-operator agreement was moderate-very good for casts (0.58–0.82) and good-very good for digital models (0.65–0.92). Intra-operator agreement with IOFTN sub-categories (1–14: feature of malocclusion) was good-very good for casts (0.70–0.97) and digital models (0.80–0.94). Inter-operator agreement was moderate-good for casts (0.53–0.77); and moderate-very good for the digital models (0.58–0.90).

Conclusions

Digital models are an acceptable alternative to plaster casts for examining the malocclusion of patients requiring combined orthodontic-orthognathic surgical treatment and determining treatment need.